Terminal equipment such as satellite receivers, set-top boxes, Wi-Fi access points, mobile telephones and the like, referred to generally as terminal devices, contain an electronic identity module referred to in general as an identity module (IM) or ID unit, more specifically user identity module (UIM) or R-UIM. Some identity modules may be referred to as smart cards. Mobile telephones, particularly those based on the Groupe Speciale Mobile (GSM) Standards, contain an electronic module, known as a subscriber identity module or SIM. The SIM can be either a smart card, which has the well-known size of credit cards, or alternatively it can be in a much smaller format, called a “plug-in SIM. The latter format is more suitable for handportable terminal equipment. Although, all the of the terms identity module (IM), user identity module (UIM) or R-UIM. may be used, hereinafter the term SIM will be used for convenience to reference all terms referring to a module or ID unit, of whatever physical form, that contains data identifying the account and/or the user or subscriber. However, the use of the term SIM should not to be deemed as limiting in any way.
A mobile telephone may also be referred to as a mobile terminal or more generally a mobile station (MS), which includes a mobile equipment (ME) plus the SIM. Hereinafter the term mobile equipment (ME) will be used. However, this term is not deemed to be limited. For example, embodiments of the present invention may be used in relation to a satellite receiver or similar set-top box, which may not be mobile.
The SIM stores data to be used by the terminal equipment. The SIM is pre-configured to contain a unique identifier for a particular user, and may also contain appropriate authentication functions. The SIM is also able to store temporary data such as paging messages and a number directory.
In current GSM based systems, the subscriber identity is not linked to the mobile station (MS). The connection between the subscriber and the MS is accomplished by the use of the SIM. The SIM is a module, or smart card, that installs in the ME and has a unique user identity information. In the case of a prepaid card, the issuer typically does not inquire as to the identity of the customer, so that the smart card contains information identifying to the network only the wholesale account of the issuer of the prepaid card and the source of the call is identified only by the IMEI, discussed below.
GSM based systems allow users to insert their SIM card into any mobile station and be recognized by the GSM network via information on the SIM rather than information associated with the particular terminal in use. In this system, the mobile equipment is identifiable by an IMEI (International Mobile Equipment Identity); however, queries to check this information are ‘expensive’ in terms of processing and are not normally verified on a per call basis.
U.S. Pat. No. 5,907,804 issued to Schroderus et al. on May 25, 1999, assigned to an entity owned by the assignee of the present invention and incorporated herein by reference defines a method and apparatus for checking the identification number of a mobile subscriber. Schroderus et al. describes embodiments in which the subscriber identities and terminal equipment are permanently connected to each other as mobile stations and in which subscribers and terminal equipment are not permanently connected together.
In the GSM system, the codes relative to the operator of the network and the user (customer) of the telecommunication network have been stored in the so called SIM. The SIM is generally a part of a so called SIM card having an electric coupling system for attaching the card to the mobile equipment. The SIM includes, for example, the information required for the communication concerning the user, the telecommunication network to be used, and the encryption of the radio data transmission. The SIM includes also the customer's invoicing data to be transferred to the telecommunication network simultaneously with the call from the mobile station. In this way the user can use the SIM card as needed in different mobile equipment, unless the use of the mobile equipment is restricted, for example, so that the mobile station can be used only if a SIM card of a certain operator or prepaid service is inserted into it. If the use of the mobile station or some of its features is restricted in the above mentioned way, the restriction will be implemented with codes stored in the SIM.
Currently, the pre-paid purse or value resident on the SIM card could be used indefinitely without exhausting the stored number of prepaid minutes when inserted in a standard GSM terminal because a standard terminal is not required by the GSM specification to have means for decrementing the number of prepaid minutes. The MS transmits to the network information from the SIM card, such as the identity of the wholesale account that has paid for a bulk quantity of network time. The amount of time used by an individual subscriber will not ordinarily exceed that bulk time during the course of a call, so that any monitoring mechanisms in the network will not be alerted. In a prepaid scenario, it is necessary that the smart card (SIM) only work with the terminal equipment or group of terminal devices that support the pre-paid decrementing engines (or equivalently that the SIM does not work with a ME that does not have a decrementing engine). Currently the GSM specification does not define a procedure to allow the pre-paid subscription card or other tangible medium that stores the number of pre-paid minutes to challenge a terminal device in which it is inserted and to reject a terminal device that does not support the decrementing of stored units.
Therefore, there is a fundamental problem with pre-paid applications utilizing the GSM technology where value is stored in the SIM card. The GSM specification allows the MS to recognize and allow/disallow registration with certain SIM cards for carriers that realize sunken costs within subsidization models, but there is nothing specified to date that allows for the SIM to recognize and allow or disallow registration with certain terminal devices.
The pre-paid carriers will load certain SIMs with arbitrary values to be used as airtime and those values will be decremented in conjunction with the ME=s prepaid engines whose job is to calculate and pass such timing data. Therefore it will always be necessary for a pre-paid SIM to be mated with a ME having a pre-paid engine; otherwise the pre-paid SIM could be inserted into any GSM ME and make free calls without any decrementation of value.
U.S. Pat. No. 5,748,720 issued to John Loder on May 5, 1998, assigned to an entity owned by the assignee of the present invention and incorporated herein by reference defines a removable subscriber identification module for a mobile radio terminal. An ability to hold a record of the amount of funds prepaid for at the point of sale is incorporated within a SIM. This payment record will progressively decrease as services of the network are used according to a tariff rate which is which is either preprogrammed into the SIM or sent by the network. The SIM monitors the remaining value of the payment and, when the value of the payment reaches a predetermined minimum value, prevents further calls. This blocking of the mobile station MS may be effected by a specific blocking command outputted to a mobile equipment part of the mobile station, or by disabling network operation functions, such as authentication algorithms in the SIM, or by not sending a specific acknowledgment to the network. U.S. Pat. No. 5,600,708 issued to Meche at al. on Feb. 4, 1997, assigned to the assignee of the present invention and incorporated herein by reference defines a mechanism and method by which a mobile station which has been determined to be stolen can be locked to the SIM inserted in the unit and thereby be made less valuable in terms of re-sale. The mobile station (MS) of Meche et al. is locked to the SIM by an over-the-air command. Additionally, the Meche et al. invention provides a system wherein a SIM inserted in a mobile station may be locked to the mobile station=s IMEI, thereby making the SIM usable only in the mobile station to which it is locked. The Meche et al. invention requires queries to determine if the IMEI is on a list of stolen or otherwise unacceptable mobile stations. Thus, there is a need for an apparatus and method where only approved pre-paid MS=s are used in conjunction with their pre-paid SIM cards.
Other art assigned to an entity of the assignee of the present invention and incorporated herein by reference are:
U.S. Pat. No. 5,956,633 issued to Pertti Janhila on Sep. 21, 1999.
U.S. Pat. No. 6,427,073 issued to Kortesalmi et al. on Jul. 30, 2002.